A number of prior works on learning \(\omega (s,a)\)  (e.g. DualDICE [1]}, GenDICE [2]}) can be viewed as variants of the above minimax objective, with some additional regularization terms on \(\omega (s,a)\) .
For example, there is an additional \(\frac{1}{2}\omega ^2\)  term in DualDICE to penalize \(\omega \)  so that the resulting MIW values \(\omega (s,a)\)  will not be too large.
This term thus serves as a regularization.
